The tip of a biopsy needle is often not clearly discernible using a standard ultrasonic scanner. We are attempting to devise a means of vibrating or rotating a biopsy needle to permit visualization by color Doppler-flow ultrasound during clinical procedures. Last year, we constructed a device using a modified speaker coil. The colored regions produced by the vibration were found to be unsatisfactory. This year, we developed two other types of devices for producing small mechanical disturbances to improve visualization.